Abstract

The foodborne pathogen Salmonella enterica serovar Typhimurium was subjected to starvation in seawater microcosms for three years to study modifications in its outer membrane and extracellular protein profiles. After incubation, outer membrane proteins and extracellular proteins profiles of stressed bacteria were found to be altered when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). These modifications were shown by the appearance of bands, as well as the level of expression of certain proteins. The expression levels of sopE2, invA, sipA and sopBvirulence genes were also studied by reverse transcriptase polymerase chain reaction. Our findings showed that the expression level of sopE2 was slightly decreased under starvation. Whereas the quantities of sopB mRNA were increased in the two starved strains S1 and S2. The expression of sipA was decreased in strain S1 after starvation, but was significantly increased in strain S2.

Key words: Salmonella, starvation, alteration, outer membrane protein, extracellular proteins, virulence gene expression.